Equalizer Star Of Denon Av Controller

Sometimes in this era of audio and video marriages, you need a marriage counselor. Not that your TV monitor and audio system emulate the Bickersons, but often they need aid in communicating.

Enter the Denon AVC-500II, described as an ''AV Control Center.'' This $375 black box the size of a small receiver sprouts more knobs, push buttons and sliders than marriage counselors spout psycho-babble.

The AVC-500II includes inputs for three audio-video sources, such as VCRs and videodisc players, plus an audio-only line input, which can be used for a CD player. A unique feature missing from other AV controllers is a five- band graphic equalizer.

A graphic equalizer works like common bass and treble controls, but over several separate areas of the audio spectrum. A video enhancer circuit can be switched in to improve some noisy pictures, such as the video from a poor- quality tape. Four audio modes offer the choice of normal stereo, synthesized stereo, synthesized surround sound and genuine Dolby surround sound. A separate switch selects whether this special audio circuitry enhances sound being dubbed onto a tape.

A large volume knob is really two concentric knobs individually controlling the level of front and rear channels. Two balance knobs separately vary the left to right balance of front and rear. A switchable dynamic range expander increases the difference between loud and soft on the front channels, compensating for the compressed nature of most video sources.

An input level control adjusts whatever source you may connect for lowest distortion and least noise.

A desirable feature, not obvious from all the front panel controls, is the 25 watts per channel (into 6 ohms, an unusual rating, at 1 percent distortion) amplifier. This makes for a self-contained stereo video system, or using a receiver or amplifier you already own, a four-channel surround sound system.

The AVC-500II matches any AV control center-surround sound unit on the market in versatility. There's little in the way of mating audio and video components that this Denon can't do. Dubbing between VCR's, or from videodisc VCR, is a breeze. It lacks only remote control.

The relatively modest price of the Denon belies its highly satisfactory performance. While not comparable in performance to the $500 NEC or $600 Shure AV surround sound models, it's also considerably less expensive, while offering more features.

Although an equalizer often proves unnecessary on an audio-only system, the audio that comes with video, such as on TV broadcasts or videotape, often needs tonal doctoring.

The Denon tends to exaggerate high-frequency noise more than is desirable, with a tiny bit of hiss at the high frequencies. Denon specifies the signal-to-noise ratio at only 90 decibels, which is less than a good audio-only amplifier.

Of course, the high-frequency hiss is easy to control with the 16 kilohertz slider of the equalizer. The surround synthesizer fails to provide very impressive results. The Dolby surround works well.

The sheer number of controls makes the unit difficult to operate. Most annoying is the volume control. The two sections controlling front and rear lack a friction clutch so that you must grasp both firmly if you wish to change front and rear volume simultaneously while keeping the same balance.

The AVC-500II appears well constructed, as are virtually all Denon components. Although the name Denon may not be as common as Sony or Technics, it is a large concern in Japan, also known as Nippon Columbia.